Stimuli-responsive polyurethane bionanocomposites of poly(ethylene glycol)/poly(ε-caprolactone) and [poly(ε-caprolactone)-grafted-] cellulose nanocrystals

In this study, in situ polyurethane (PU) bionanocomposites of poly(ethylene glycol) (PEG)/poly(epsilon-caprolactone) (PCL) polyols, bare cellulose nanocrystals (CNCs) and PCL-grafted CNCs (G-CNC) were synthesized with different contents of CNCs as cross-linking agent to control the extent of phase separation. The effect of confining the chains between CNCs through urethane linkages and presence of PCL grafts on phase and crystallization behavior was evaluated. Crystallization and chemical networking were controlled to tune the shape fixity (SF) and recovery (SR) of the specimens, resulting in a SF of 100% for linear and PU nanocomposites of G-CNC (0.5% and 1%) samples. The PU nanocomposite of G-CNC (0.5%) was selected as the optimum sample with the highest SR of 100%. The effect of surface hydrophobicity on cellular behavior of Human Foreskin Fibroblast (as a normal cell) and HepG2 (as a cancerous cell) cells was evaluated. Cell adhesion analysis of the prepared samples indicated two different behaviors possibly due to the difference in the epigenetic nature of the cells and cellular integrin- based bonds showing a great potential for a variety of tissue engineering applications.